alleryStart learning →A clock tower's clock has a radius of 1.0 m. Through what angle does the hour hand rotate going from 12 p.m. to 3 p.m.?
Api/4 rad
Bpi/2 rad
Cpi rad
D2pi rad
Answer & Solution
Correct answer: B. pi/2 rad
1. Going from 12 to 3 covers 1/4 of the 12 hours the hour hand needs for a full revolution.
2. A full revolution is 2pi rad, so the angle covered is (1/4)(2pi) = pi/2 rad.
3. That is equivalent to 90 degrees.
_Source: OpenStax Physics (CC BY 4.0), Ch 6 "Circular and Rotational Motion", section 6.1 Angle of Rotation and Angular Velocity_
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